Well,
Ok, perhaps he could of introduced himself a bit better. But I thought this forum was set up to help everyone large or small. :

There are many topics on here that ask for How much to do this, Price for this... so so many.
Frank,
If you can work out the number of hours it would take to do then your nearly there.
Just an example lets say it took 1 person to do all of that 6 hours
You could hire 3 people and devide it into shifts of 2 hours each. Total of 6 hours. Plus that way you have cover if one person does not turn up.
Now we cant say how long it will take, because of the layout, density, things scattered about in the classrooms.. etc etc. All these thing matter.
Types of flooring, number of desks... not sure if you have to polish the desks etc etc.
So after you work out the number of hours you add on you cost for bin liners, paper towels etc as seperate. Dont forget about all the chemicals you will use. Or is this going to be in your hourly rate.
And yes you will need a tight H&S. When you submit the tender include everything insurance, number of staff etc.
Now the one who will win this will be someone that will be the cheapest. But one that can also do it the safest without the fuss.
Large companies spread the cost of jobs accross several jobs. This way they keep lare jobs down in price.
I would say somewhere around £11.00 per hour as it will be a large job and other will want this. It could even be alot lower like £8.50. You might be lucky to get away with 12% profit. But have ago
Best of luck.
Dave